Purified streptococcal pyrogenic exotoxins (SPE) A, B, and C well be produced by a method based on precipitation with ethanol and differential solubility in acetate buffer at pH 4.0 followed by flat-bed isoelectric focusing. Passive hemagglutination and hemagglutination inhibition assays will be used to determine the distribution of A, B, and C toxins among rheumatogenic group A streptococci from various geographical areas. Further studies on the kinetics of toxin production in a variety of media will be pursued. Various techniques for the detoxification and preparation of multivalent toxoids ultimately to be used for human immunization will be examined. Amino acid sequencing of the purified toxins may reveal homologies among the toxins and known peptide hormones; such studies may help determine target sites for the toxins. The possibility that this family of low molecular weight proteins modifies the host response by acting as hormone analogues will be studied. The mechanism of blast transformation relative to the nature of the receptors and the cellular mechanisms activated is to be investigated. Studies will be initiated on the genetic mechanisms, including transduction, transformation and the extrachromosomal plasmids in the control of SPE production. The mechanisms of pyrogenicity and the enhancement of endotoxin shock by this group of exotoxins will be studied using a pharmacologic approach. An in vitro model designed to test the immunosuppression of these exotoxins will be used to determine the effects of the toxins on cell populations including macrophages B cells and T cells.